Feed adjusting means for hammer mills, pneumatic conveyors and the like suction-operated means



"`n. 13, 1960 J, ABONENC 2,964,359

FEED ADJUSTING MEANS FOR HA MER MILLS, PNEUMATIC CONVEYORS AND THE LIKESUCTION-OPERATED MEANS Filed Oct. 4, 1955 3 Sheets-Sheet 2 L a W57?? gATTORNEY 5 Dec. 13, 1960 J. ABoNNr-:Nc 2,964,359 4 FEED ADJUSTING MEANSFOR HAMMER MILLS PNEUMATIC l coNvEYoRs-AND THE LIKEsucTIoN-OPERATEDMEANS Filed oct. 4. 1955 s sheets-sheet s ATTORNEY SiUnited States PatentfO FEED ADJUSTING MEANS FOR HAMMER MILLS,

PNEUMATIC CONVEYQRS AN D THE LIKE SUC- 'rIoN-orEnATED MEANS JeanAhonnenc, Luc-en-Diois, France Filed oct. 4,1f955,ser.fNo. 538,499Claims priority, application France Oct. 15, -`1954 7 claims. (ci.soz-+36) ,Percussion Crushers and hammer mills require for the removalof lthe material crushed therein a`powerful -suction adapted 'to emptytheV crushing chamber and to convey the crushed material further on.`The capacity of production of such machines is highly variable. `Itdepends on the size of the openingsin the grids and on ythe nature ofthe materials to be crushed, thel said v4materials differing as to theirspecific weight, hardness and `contents of cellulose or the like fibres.

The maximum efli'ciency of a`crusher is reached at the thresholdof clogging. This clogging occurs when the suction is no longer `suflioient`for ,the removal and the .'co'nveyanceof the 4crushed material. Whenone operates beyond this threshold, in the case of an excess amount ofmaterial entering the apparatus, the suction is out oli entirely ornearly so. This ,leads to a very 4'large demand fordriving power which,in the case of a crusher controlled byan electric motor, may produceoverload operation of the circuit-breaker controlling the circuitfeeding the motor. It is then necessary to unclog the'crusher by handtogether the suction means, before resuming operation. In practice, theattendants or lthe automatic means controlling the input of materialinto the Crusher operate with a high margin of safety so as to avoid Vaclogging, but the yield obtained is then lower than that actuallyobtainable using the full efiiciency of the machine. i

` My invention hasfor its object feed-adjusting means applicable tomachines operating under suction and chiey to hammer mills and pneumaticconveyors, and adapted to feed themachine in .a uniform and `constantmanner at the `limit of its capacity before clogging, whatever r'may bethe material to be crushed, provided it is of a pulverulent nature andcapable of being conveyed pneumatically.

To this end, the material to be crushed or conveyed is fed into arectangular opening located in a horizontal plane inside a casing out ofwhich the said material cannot ow Y through gravity while it is suckedout of Athe saidv casing through another rectangular opening located atthe same level or at a level above that of the first mentioned opening,the said two openings being 'separated from one another by a partition,so that the suction acts along a curvilinear path assuming the shape ofa syphon and the lowermost point of which regis ters vertically with thesaid partition at the level of a line parallel to' and in proximity withthe lower ridge of the said wall or partition, said line detining thellimit beyond which -the machine becomes clogged and corresponding tothe maximum possible yield of the machine.

To obtain this automatic regulation of the feed of the machine forcontinuous operation at maximum yield, lthe ridge of the partitionseparating the two openings serving for the `feeding 4and the suctionrespectively, 4farms the control member operating through the agency ofone or more level detectors. The said detectors, which may beadvantageously of an electronic type,

hold the lowermost point of the suction 'curve near the threshold ofAclogging by acting on the feed of the machine, the driving motor ofwhich remains continuously operative.

The feed of the machine may be adjusted gradually through a modificationof the `cross-section lof Ithe A-passage provided for the' material vorelse through a`modi- -cation of the speed of ow of said material.

Thus, in a preferred embodiment, the detector or detectors carried bythe partition separating the two openings in 4the machine control theoperation of an electric motor which produces, through `the agency of aworm and of a lever system, the opening or the closing of a gateinserted in the feed pipe.

Although the adjusting means, according to my invention, may includeonly a maximum or a minimum detector, it is preferable to provide .itwith both types of detector.

'In a preferred embodiment, I may utilize to a maximum and minimumdetector comprising two light beams extending 'across the syphon-shapedcurve andV produced by ftwo sources of light arranged laterally atoneside of the `syphon so as to impinge on corresponding photocells on theopposite `sideA of the said ysyphon, the vvertical spacing between thetwo sources' of light being adjustable, so as .to allow` formodification of the ditle'r ence between the maximum and the minimumpermissiblelevels ofthe material. I

'ln a further embodiment, the maximum and minimum detectormaybeconstituted byadetector' of the lpresence of the `material associatedwith a beam' produced -by `a source of light and limpinging on'aphotocell, theV said detector .and saidb'eam being verticallyydim'ensioned to define, respectively the maximum limits and theminimum, or conversely.

According to a still further feature of my invention, the adjustingmeans includeat least one Vadditional air intake formed at a point ofthe flow path feeding the material'to be crushed into the input of thecrusher so as to allow a suction to be exerted onthe material in thecase of a temporary fortuitous clogging of the actual adjusting means.This air intake is constituted preferably by an opening formed in one orin both of the two side walls ot' the adjusting means at a level suchthat its center is located substantially in register with the linedefining the threshold of clogging.

The additional air intake may also be formed by an elongated slot in thewall of the adjusting means on the downstream side of the syphon orelse, by a channel opening ahead of and 'underneath the partitionseparating the two openings corresponding respectively to the admissionand to the suction of the material through the adjusting means while aap engaging the said channel allows adjusting not only the flow rate ofthe additional air but also the average ow rate through the machine.

Such additional air 4intakes may be used either alone .or in combinationwith a further additional air intake 'formed in the wall of theadjusting means on the downstream side of the suction opening.

This latter air intake may extend throughout the breadth 'of theadjusting means and may preferably take the form ofi an auxiliary syphonprovided with a ap which allows adjusting the input of air while thematerial which may drop out fortuitously during the suction stage intothe air intake, collects at the bottom `of the said auxiliary syphon.

1 have illustrated diagrammatically by way of example in accompanyingdrawings various embodiments of my improved arrangement. In saiddrawings:

Figs. 1 and 2 are respectively front and side elevational partlysectional views of a crusher provided with a lateral input and with theabove referred to adjusting means;

Fig. 3 is a longitudinal sectional view of a pneumatic conveyor providedwith similar adjusting means;

Fig. 4 is a perspective view of the simplest embodiment after removal ofone of the side walls of the spyhon;

Fig. 5 shows on an enlarged scale the same embodiment in longitudinalcross-sectional view;

Fig. 6 is a general perspective view of the means for adjusting the fiowrate;

Fig. 7 is a diagram showing the possible modifications of the curvedefining the air passage;

Figs. 8 and 9 show two detectors for sensing the presence ofthe materialin the syphon;

Figs. 10 and 11 show two maximum or minimum detectors utilizing aphotocell;

Figs. l2, 13, 14 show three different forms of maximum and minimumdetectors;

Figs. 15 and 16 are longitudinal sectional views of two alternativeimproved embodiments of the adjusting means.

Figs. l and 2 illustrate a crusher having a lateral input of aconventional type and with which the adjusting means according to myinvention have been incorporated.

In said gnres, 70 designates the body of the crusher, 71 the crushingchamber inside which the hammers 72 rotate, said hammers being carriedby a shaft 73 adapted to revolve at a high speed.

74 designates the grate closing the crushing chamber at its lower end,and through which the crushed material drops onto a sloping surface 75ofi' which it is sucked through a suction opening 76 into a shell 77under the action of the bladed rotor 78 of a suction device, while 79designates an additional air intake through which it is possible tosweep the material ot the grate of the crusher.

The feeding of said crusher is performed through a hopper 80 locatedabove it and the lower end of which is provided with a distributor 81including a gate 82 controlled by a lever 83 actuated through a nut 84adapted to move vertically over a threaded member 85 driven intorotation bv a motor and speed reducing group 86. 87a and 87b designatetwo stops defining the stroke of the nut 84 and consequently that of thegate 82.

4The adjusting means forming the object of mv invention are insertedbetween the distributor 81 and the upper section of the casing of thecrusher 70.

Said adiustinr means are constituted as illustrated in Figs. 4 and 5 bva casing 2 formed by walls defining with one another three openings, towit:

A first opening A of a rectangular shape located in a horizontal plane,which opening serves as an inlet for the feeding of the material intothe arrangement;

A second opening B of a rectangular cross-section having the same sizeas the opening A and located in a horizontal plane coplanar with thefirst mentioned plane of the opening A or lying in proximity with thelatter and separated from the said first opening A by the ridge C-Dforming the lower edge of the downwardv concavely curved partition 2defining the upper surface of the suction channel, the said opening Bbeing the suction opening;

A third opening C of a rectangular cross-section located in a horizontalplane and separated from the second opening bv the ridge G-H forming theunper edge of the upright partition 63. the said third opening providingfor the delivery of the pulverulent material down- Wardlv into thecrusher or the like machine (see Figs. 1 and 2);

These three openings A, B, and C lying in horizontal planes are definedin practice and as apparent from the drawing, by the gaps between thedownwardly concave partition 2, the rear wall of the casing and thefront wall or partition 63 thereof.

The arrangement of the horizontal planes provided with the openings A, Band C associated with the bottom 5, with the curved wall 2 and with thevertical partition 63 terminating with the ridge G-H, defines the syphonforming the adjusting means.

When the material to be crushed enters the regulator as illustrated bythe arrow 1 shown in Fig. 1, it passes through the feed opening A anddrops into the bottom 5 of the casing and it is then sucked through theopening B in the direction of the arrow 6 of Fig. 1. The path followedby the upper surface of the material inside the adjusting means crossesconsequently the vertical plane extending perpendicularly to theopenings A and B between the latter and through the ridge C-D. The lineE-F shows the intersection between the said path and the said verticalplane, said line E-F being parallel with the ridge C-D.

If the flow rate of the material conveyed is low with reference to thecapacity of the machine, the line E-F sinks away from the ridge C-D. Ifthe ow rate increases, the line E-F rises towards the said ridge C-D. Ifthe ow rate is too high, the said line E-F coincides with the ridge C-D.This leads to a clogging of the arrangement as a consequence of thecomplete closing of the gap through which the material is sucked in, asdefined by the four-sided polygon C--D-F-E.

It should be remarked that, when the ow rate increases, i.e. when theline E-F rises towards the ridge C-D, there is a moment at which thearrangement is on the threshold of clogging. The line E-F registers thenwith a limit line which is designated in Fig. 1 by X-Y. The said linedefines with the ridge C-D the normal suction gap ensuring maximumefficiency of the machine.

The adjusting means described are such that the lowermost point of thecurve followed by the material is permanently tangent to the said lineXY, said means i11- cluding to this end a detector of levels located onthe said line so as to allow adjusting accurately the flow rate throughthe machine by constraining the line E-F to coincide with the line XY.This provides for maximum efiiciency without any risk of clogging.

The level detector may be a detector of the photocell type or anelectronic presence detector. The said detector may act, as shown inFig. 6, on an electric motor 8 adapted to revolve in both directions andwhich, when started, drive a worm 9 which produces a translationalshifting of a nut operatively associated with a lever 12 pivoted at 13so as to produce, according to its direction of movement, the opening orthe closing of a gate 14 located at the end of the channel 15 openingabove the feed-adjusting means. Switches 16 and 17 controlled at theends of the strokes of the unit in either direction produce a stoppingof the motor in correspondence with the closing and with the opening ofthe gate 14 respectively and they ensure simultaneously the desiredsafety by showing acoustically and/or optically that the feeding silo orthe like is empty while the gate remains open, or reversely, that theadjusting means are still clogged While the gate remains closed.

It should be remarked that, in order to prevent any too sudden orfrequent reversal of the motor controlling the feed of the adjustingmeans, which would lead to a constant beating of the adjusting gate 14,it is possible to provide maximum and minimum detectors which allowstabilizing, as illustrated in Fig. 7, the fiow rate to either side ofthe line X--Y between two lines corresponding to the allowed maximum andminimum rates.

The presence detectors 21 illustrated in Figs. 8 and 9 are adapted toact on the feeding of the machine accord'- ing as to whether they arecovered or not by the material Ato be conveyed. The said detectors 21are located at an adjustable height inside the syphon 22 so that themaximum or minimum defined by the said detector may be modified asdesired.

In the case illustrated in Fig. 10, the maximum or minimum detector isconstituted by the combination o-f the source of light 23 with thephoto-cell 24; the said source and photo-cell are arranged to eitherside of the body 25 of the syphon and the luminous Vbeam produced by theprojectors 23 impresses the cell-24 across thefs'aid t syphon, the twowalls of which Vare provided with openings 26 facing each other.`According as to whether the beam of light 28 from the projector'23 iscut ofi or not by the material 29 inside the syphon,` and consequently,according as to whether the cell 24 is illuminated or' not, the saidcell will act on the feeding of material into the syphon so as to reducethe throughput if the detector is a maximum detector or to increase theflow rate if the detector is a minimumdetector.

When adjusting the maximum or the minimum, it is suiiicient to shift theprojector 23 in the direction of the arrow 311 of Fig. lO, thetransparent plates 27 allowing a slight shifting of the luminous beam.

In the case of the modification illustrated in Fig. l1, the adjustmentof the maximum or of the minimum is obtained through a modification ofthe angular position of the projector 23 and consequently through amodification of the angular setting of the beam of light.

A maximum and minimum detector may be constituted, as illustrated inFig. Vl2, by two sets of projectors and photo-cells. The two projectors32a and 32h are located above each other at different levels on theright hand side and on the left hand side of the syphon respectively, so

as to produce luminous beams 33a and 33b adapted to impress the twocells 34a and 34b registering with the said projectors and also locatedat different levels. The cell 34a controls the reduction in the ow rateat the input end whenever the beam 33a is cut off by the material insidethe syphon 35. The cell 34h controls, in contradistinction, the increaseof the flow rate `at said input end whenever the beam 34h is no longercut off by the said material. The level of the material 36 inside kthesyphon is thus constrained to move within narrow limits to either sideof the dot-and-dash line x-y.

The adjustment of the average fiow rate to either side of the said linex-y may be obtained by modifying the location of the projectors 32a,3-2b the level of which may be adjusted with reference to that of thecorresponding photo-cells 34a, 34h.

In the case where the products to be sucked out form a very irregularsheet or in the case of a machine having a very large cross-section, itis possible to reso-rt to the maximum and minimum detector systemillustrated in Fig. 13. The two projectors 37a and 37b are located inthe central part of the syphon, above each other, while the beamsproduced by them as shown at 38a and 38b are adapted to impinge on thecorresponding photo-cells 39a and 3911 located to either side of thesyphon 41, the cell 39a defining the maximum flow rate, the cell 39bdefining the minimum flow rate.

The adjustment is performed as precedingly through a shifting of theprojectors 37a and 37b which are both housed inside a common casing'42.

Obviously, only one of the projectors may be located at the center ofthe syphon, the other being located laterally as illustrated in dottedlines in Fig. 10, or else the two projectors may be located on theoutside of the syphon and the two cells inside the central casing 42.

As to the maximum and minimum detector illustrated in Fig. 14, it isconstituted by a member 43 subjected to modifications in capacity anddeiining the maximum flow rate, the said member being associated with aprojector Obviously, the reverse solution is possible, in other Words,

agees-5,@

d the. minimum may be deteotedby the member subjected to modilicationsin capacity ywhile' the maximum is detected'by the luminous beam.

As illustrated in the drawings, the lateral openings 26 of the syphonare not closed, although they may be closed by transparent plates. Theseopenings serve, as a' matter of fact, not only for the passage of theluminous beams adapted to detect the maximum and the minimum, but alsoThey allow cleaning the lenses of the projector, which prevents any dustdeposit from forming and thus giving erroneous results in the detection,since the suction produced in the syphon does not allow the material toescape through the openings 26 and the stream of air produced in thevicinity of the said openings ensures a permanent cleaning of thelenses;

The said openings form additional intakes which allow, in `the case of afortuitous clogging of the syphon, an automatic release of the saidclogging; to this end, the centers of the two openings 26 which arecoaxial, lie substantially at the level of the line x-y corresponding tothe limit of clogging.

The two additional air intakes thus formed are advantageously completedby a further air intake formed by a slot S4 provided in the wall 50 ofthe syphon (Fig. l5).

However, in order to prevent on the one hand any introduction of foreignmaterial inside the regulator through the channel 53 and on the otherhand any passage of the material undergoing treatment through the saidadditional air intake or slot 54, which passage may occur fortuitouslyeither because the material subjected to suction follows the curved wall50 or else, because in a hammer m-ill, the crushed material may beprojected in the direction of the arrow 55, I resort preferably to thearrangement illustrated in Fig. 16.

The wall 52 of the channel 53 lying ahead of the in curved wall 50 hasin this case at its upper end an incurved section 56 forming a reversedsyphon associated with a plate 57 the position of which may be adjustedthrough the levers 58 so as to modify the amount ofair entering throughsaid additional air intake.

Furthermore, at the level of the slot or additional air intake 54a, thewall 50 of the adjusting means carries downwardly curved plate 59extending above a trough 61 inside which may collect any materialprojecting outside the main syphon underneath the Wall S0. This trough6l may be adjusted as to position through a lever 62 so as to allowregulating the amount of additional air entering the adjusting means.

A further additional air intake may be constituted, as illustrated inFigs. 15 and 16, by a transverse partition 52 arranged vertically andthe lower ridge of which extends downwardly into the opening A definingthe input of material and is located at a level lower than that of thelower ridge of the wall 50. The two Walls 52 and Si) form together avertical channel '53 extending transversely throughout the breadth ofthe arrangement so as to form this further additional air intake.

It is apparent that when the level of material inside the adjustingdevice reaches the lower ridge of the wall 52 and the machine isclogged, the air sucked in through the lchannel 53 allows a speedy`release of the said clogging.

The adjustment of these different additional air intakes allowsmodifying simultaneously the average throughput of the arrangement. As amatter of fact, if, during nor'- mal operation, the average level of thematerial lies on the line defined by the cross shown in Fig. 16, and, ifthe additional air intake is throttled without any reduction in theamount of material fed into the arrangement, the level vof the materialinside lthe latter drops. For restoring the level, it is, consequently,necessary to increase the ow rate.

ape-gasa Reversely, if the additional air intake is opened to a widerextent without any modification of the feed, the level of the materialinside the arrangement rises. It is, therefore, necessary to reduce theflow rate of material so as to restore the level to the desired value.

The closing and the opening of the additional air intake may becontrolled from a distance by an auxiliary motor and by a worm or else,through any other suitable mechanical means.

The arrangement described may also show the following auxiliaryfeatures:

It includes at least in one of its side walls an inspection gate 18(Figs. 4 and 7),V wherethrough it is possible to inspect the level ofthe material and also to make sure that no foreign body shown at 19 andcollecting at the bottom of the syphon formed by the ridge C-D reaches alevel corresponding to the clogging area. The removable bottom of thecasing allows also emptying the latter from time to time so as to removesuch foreign bodies at 19;

The wall 63 the upper edge of which forms the ridge G-H separating thetwo openings B and C, may be adjustable and the same is the case for theupper incurved wall 2 guiding the material through the syphon. As amatter of fact, as illustrated in Figs. 4 and 5, the said wall 63 may bevertically slidable inside the regulator and the upper wall 2 may bepivotally secured along a horizontal line 64. It is thus possible toshift the ridges C-D and G-H. These adjustments allow modifying thecurve followed by the material entering the feedadjusting means. Bylowering the wall 63 with the ridge G-H or by raising the Wall 2 withthe ridge C-D, the entrance of heavy material inside the regulator ismade easier. Obviously, however, the input curve for the material shouldnot be such as might allow the latter to enter through mere gravity,since the syphon would no longer act as a clogging-limiting member andas a member preventing the entrance of foreign bodies;

To allow the material entering the adjusting means to be subjected tosuction while it assumes the shape of a uniform layer, it is ofadvantage to provide in proximity with the bottom of the adjusting meansand underneath the admission opening A a rotary member which ensures asuitable distribution of the material. Thus, the material reaches theadjusting means and consequently the crusher, as a layer of a uniformthickness and of a breadth corresponding to that of the input end of thecrusher. Such a distribution is, furthermore, of considerable advantagefor ensuring maximum eiciency for the crusher.

As stated hereinabove, the feed adjusting means according to myinvention are adapted for use not only on hammer actuated crushers butwith all suction means such as chiey pneumatic conveyors.

Such feed adjusting means are, in fact, shown in the case of the-application illustrated in Fig. 3, where 89 designates such a pneumaticconveyor pipe, in which the suction is exerted in the direction of thearrow 91. 92 designates a gate closing normally the conveyor pipe 89ahead 4of the lateral opening 93 to the periphery of which are securedthe adjusting means. 94 designates a cover which normally leaves theopening 93 uncovered but allows if required closing the latter if thepipe 89 is to convey a product fed from a supply ahead of the gate 92.

What I claim is:

1. An adjustable syphon controlling the flow of granular material,comprising a channel having an upper arcuate downwardly facing concavewall, means for feeding the granular material into one end of thechannel longitudinally of the latter along lines extending in verticalplanes round the lower edge of the corresponding end of said upper wallto urge said material through the channel, suction means adapted to drawthe granular material out of the other end of said channel, the suctionline defined by the upper surface of the material flowing through thechannel following an incurved path the concavity of which is directeddownwardly and the lowermost point of which at the first-mentioned endof the channel registers vertically with .the lower edge of the upperwall of the channel at said first-mentioned end of the channel, at leastone detector sensitive to the level of said lowermost point of thesuction line with reference to a transverse horizontal line passingalong said lower edge of the upper wall of the channel and meanswherethrough said detector controls the flow of material through thematerial-feeding means to return the level of said lowermost point ofthe suction line into substantial coincidence with a predeterminedposition with reference to said transverse line.

2. An adjustable syphon controlling the ow of granular material,comprising a channel having an upper arcuate downwardly facing concavewall, means for feeding the granular material into one end of thechannel longitudinally of the latter along lines extending in verticalplanes round the lower edge of the corresponding end of said upper wallto urge said material through the channel, suction means adapted to drawthe granular material out of the other end of said channel, the suctionline defined by the upper surface of the material flowing through thechannel following an incurved path the concavity of which is directeddownwardly and the lowermost point of which at the first-mentioned endof the channel registers vertically with the lower edge of the upperwall of the channel at said first-mentioned end of the channel, at leastone detector sensitive to the level of said lowermost point of thesuction line with reference to a transverse horizontal line passingalong said lower edge of the upper wall of the channel, an electricmotor controlled by said detector and a gate controlled by said motorand controlling the flow of material into the material feeding means inaccordance with the shifting of said level of the lowermost point of thesuction line with reference to said transverse line.

3. An adjustable syphon controlling the flow of granular material,comprising a channel having an upper arcuate downwardly facing concavewall, means for feeding the granular material into one end of thechannel longitudinally of the latter along lines extending in verticalplanes round the lower edge of the corresponding end of said upper wallto urge said material through the channel, suction means adapted to drawthe granular material out of the other end of said channel, the suctionline defined by the upper surface of the material flowing through thechannel following an incurved path the concavity of which is directeddownwardly and the lowermost point of which at the first-mentioned endof the channel registers vertically with the lower edge of the upperwall of the channel at said first-mentioned end of the channel, twosources of light arranged to either side of the path followed by thematerial near the said lowermost point of the suction line, photo-cellslocated to either side of said path and subjected to the impact of theluminous beams produced by the sources of light, means for adjusting therelative position of the associated photo-cell and source systems, meanswhereby the photocells detect the rising and lowering respectively ofthe lowermost point of the suction line with reference to apredetermined line parallel with a horizontal transverse line passingalong said lower edge of the upper wall of the channel, and meanscontrolled by the photo-cells to control the ow of material through thematerial-feeding means and to return thereby the said lowermost point ofthe suction line towards the said predetermined line.

4. An adjustable syphon controlling the flow of granular material,comprising a channel having an upper arcuate downwardly facing concavewall, means for feeding the granular material into one end of thechannel longitudinally of the latter along lines extending in verticalplanes round the lower edge of the corresponding end of said upper wallto urge sa'd material through the channel, suction means adapted to drawthe granular material out of the Aother end of said channel, the suc- Qtion line defined by the upper surface of the material wing through thechannel following an incurved path the concavity of which is directeddownwardly and the lowermost point of which at the first-mentioned endof the channel registers vertically with the lower edge of the upperwall of the channel at said first-mentioned end of the channel, adetector of the presence of material, a

photocell, a source of light producing a beam impinging on thephoto-cell, said detector and photo-cell being adapted to detectrespectively one of the extreme allowed shiftings of the lowermost pointof the suction line to either side of a predetermined line parallel witha horizontal transverse line passing through said lower edge of theupper wall of the channel, and means whereby said detector andphoto-cell adjust the flow of material through the material feedingmeans to urge said lowermost point into register with the saidpredetermined line.

5. An adjustable syphon controlling the flow of granular material,comprising a channel having an upper arcu ate downwardly facing concavewall, means for feeding the granular material into one end of thechannel longitudinally of the latter along lines extending in verticalplanes round th'e lower edge of the corresponding end of said upper wallto urge said material through the channel, suction means adapted to drawthe granular material out of the other end of said channel, the suctionline defined by the upper surface of the material flowing through thechannel following an incurved path the concavity of which is directeddownwardly and the lowermost point of which at the first-mentioned endof the channel registered vertically with the lower edge of the upperwall of the channel at said first-mentioned end of the channel, at leastone detector sensitive to the level of the lowermost point of thesuction line with reference to a predetermined line parallel with ahorizontal transverse line passing through said lower edge of the upperwall of the channel and at a short distance underneath last-mentionededge, an auxiliary air intake opening into said channel, the center ofwhich intake registers substantially with said predetermined line toprovide for further suction on the material, and means wherethrough saiddetector controls the flow of material through the material feedingmeans to return the lever of said lowermost point of the suction lineinto substantial coincidence with said predetermined line.

6. An adjustable syphon controlling the ow of granular material,comprising a channel having an upper arcuate downwardly facing concavewall, means for feeding the granular material into one end of thechannel longitudinally of the latter along lines extending in verticalplanes round the lower edge of the corresponding end of said upper wallto urge said material through the channel, suction means adapted to drawthe granular material out of the other end of said channel, the suctionline dened by the upper surface of the material llowing through thechannel following an incurved path the con cavity of which is directeddownwardly and the lowermost point of which at the first-mentioned endof the channel registers vertically with the lower edge of the upperwall of the channel at said rstr-mentioned end of the channel, anelongated slot being provided across the upper wall of the channel justahead of its lower edge at said other end and adapted to provide afurther suction on the material ilowing through the channel, anadjustable flap controlling the amount of air passing through saidelongated slot, means for collecting the material passing fortuitou-slyout through said slot, at least one detector sensitive to the level ofsaid lowermost point of the suction line with reference to a transversehorizontal line passing along said lower edge of the upper wall of thechannel, and means wherethrough said detector controls the flow ofmaterial through the material-feeding means to return the level of saidlowermost point of the suction line into substantial coincidence with apredetermined position with reference to said transverse line.

7. An adjustable syphon controlling the ow of granular material,comprising a channel having an upper arcuate downwardly facing concavewall, means for feeding the granular material into one end of thechannel longitudinally of the latter along lines extending in verticalplanes round the lower edge of the corresponding end of said upper wallto urge said material through the channel, suction means adapted to drawthe granular material out of the other end of said channel, the suctionline defined by the upper surface of the material flowing through thechannel following an incurved path the concavity of which is directeddownwardly and the lowermost point of which at the first-mentioned endof the channel registers vertically with the lower edge of the upperwall of the channel at said first-mentioned end of the channel, aninspection gate opening into the channel, a removable bottom throughwhich foreign material may be removed out of the channel, at least onedetector sensitive to the level of said lowermost point of the suctionline with reference to a transverse horizontal line passing along saidlower edge of the upper wall of the channel, and means wherethrough saiddetector controls the flow of material through the materialfeeding meansto return the level of said lowermost point of the suction line intosubstantial coincidence with a predetermined position with reference tosaid transverse line.

References Cited in the file of this patent UNITED STATES PATENTS1,191,072 Fessenden July 11, 1916 1,755,490 Seymour Apr. 22, 19302,668,365. Hogin Feb. 9, 1954 2,774,637 Sylvest Dec. 18, 1956

